The present invention concerns a lifting element acting as a part of a lining made of a flexible polymeric material for a grinding mill used for grinding ores and minerals. More precisely, the invention concerns a lifting element of a grinding mill, where the mechanical properties and wear resistance of the wear protection change, when the profile of said lifting element changes due to wear, so that the service life of the wear protection increases.
The inner surface of the drum of grinding mills is plated with a wear resistant lining protecting the drum against wear caused by the grinding. Wear is caused by the ore and rock material and by the elements used for grinding like grinding balls, bars or cylinders. Materials used for wear lining include elastomeric material like rubber, composition metals like steel, or a combination thereof. The wear lining comprises protective plates and lifting elements, said lifting elements being here later referred to as lifting bars. Lifting bars extend from one end of the drum to another, the bars being fastened to the frame of the drum and they mechanically lock the protective plates onto the surface of the drum. Lifting bars having the purpose to improve the rotation of the material to be ground and the grinding elements in the mill are located more projecting than the lining on the inner surface of the drum. Therefore they receive also most of the impact stress caused by the dropping grinding elements and grinding bodies and of the abrasive wear caused by the grinding. The wear of the lifting bars decreases their protective effect for the lining and has also influence on the energy consumption and grinding quality of the mill. Calculations have shown that the intensity of the impact wear subjected to the bar decreases when the profile of the bar lowers caused by the wear.